how long it takes ECO

Ok, so I have always wondered how long it takes an ECO to make a decision after receiving an application (spouse visa application). And I got informed it takes them about 15mins.
Whereas, I always thought they usually do soo many research on the applicants. Like back ground check, co-ordinate with tax services etc to see if s/he has worked before in the UK, check with NHS, see if they have obtained free health checks when they aren't entitiled to it, travel out the country etc. Basically, co-ordinate with all other government agencies. And between all this they'd go back and forth, reading the application over n over again.
I don't know if they do all as I said above. Just kinda asking. Do they?

Thanks.

When one hands in application,different staffs working in behalf of UKBA carry out various checks both in UK and in the country where an application is made to verify that documents etc are genuine.

Inquires both in writing and phone are made in UK(for example the sponsors employers banks, government agencies etc).

Once all these are done ,( this can take up to 3 months in certain countries) the file is passed onto an ECO to make a decision to see whether the applicant should be granted or refused.

On average he takes 15 minutes to arrive at his decision once he is armed with the information he requires.

Remember they deal with thousands of these per year